A technical investigator often needs to transform initial data from such external sources as flat computer files, databases, and measuring equipment into processed data with the aid of calculations and transformations in order to make visual presentations and useful summaries. Any tool or device to help in making the link between initial data and data ready for presentation should have a number of qualities: (1) it should be sufficiently general to perform a wide variety of transformations on the data, (2) it should be able to handle data of a sufficiently generic form to be useful in a wide variety of contexts, (3) it should be simple to use, and (4) it should be reconfigurable in an interactive fashion. Simplicity of use particularly means that a user should be able to perform transformations on the data without needing to acquire specialized skills such as learning a general purpose programming language. Interactive reconfiguration is important because frequently an investigator cannot know in advance just what sort of analysis is called for. Frequently, the best course of analysis may only become evident to an investigator as it is taking place.
In the past, most successful screen based interfaces for analysis software have been limited to specialized situations where the data being passed from one point to another are either very simple or very constant in form. In other less specialized situations, unfortunately, such interfaces tend to be of little use.